Hull KR have released controversial former NSW and Australia forward Willie Mason just six months into his three-year contract.

The 31-year-old was de-registered by the Super League club a month ago after he was unable to obtain a Tongan passport that would have enabled him to come off their overseas quota.

Mason, who signed a two-year deal with an additional 12-month option, has made just six appearances for Rovers, who have now decided to cut their losses after losing patience with the wayward star.

A brief statement placed on the club's website said: "Willie Mason has left Hull Kingston Rovers with immediate effect.

"The club will be making no further comment at this time."

Mason, a colourful and controversial character throughout his career, has been in dispute with Hull KR since it was revealed he travelled to France to meet officials of Toulon Rugby Union club last month.

That trip was made after making just five appearances in Super League and without his employers' knowledge or permission.

Now Rovers are also investigating claims Mason may have met Toulon officials even before he arrived in the UK to link up with his new club.

Rovers recently stopped Mason's pay, citing a breach of contract by discussing a potential move, and the player has not been seen at Craven Park since handing in a transfer request.

Having being de-registered by the club last month to make way for the re-signing of Australian scrum-half Michael Dobson, he had been training alone in the club gym.

The ex-Canterbury and Sydney Roosters prop arrived at the club in March amid a blaze of publicity and made an immediate impact with a man-of-the-match display in Rovers' 40-22 win over Crusaders but his form quickly deserted him.

Big-spending Toulon are thought to have offered Mason a deal which would see him almost quadruple his wages, to around STG395,000 ($A600,000) a year.

Rovers hope to recover the majority of the wages they have paid to the player so far, possibly through compensation from Toulon should he sign for them.

Brought to you by AAP © 2024 AAP